I believe news shows will do anything they need to to get better ratings. I'm not sure if they would completely lie about any certain issue, (unless it's something extremely significant) though I do think that they would "fib" about issues, slightly exaggerating or under exaggerating some smaller details. I do believe that they would withhold a lot of information if they felt like it, though. And, for all I know, the government may be preventing news shows from broadcasting certain reports.. I, myself, do not have enough information to make a definite conclusion.
Think of it this way, if someone tells you that their spouse never disagrees with them what do you think? Obviously someone is not being heard. If you tell me there is no difference between news agencies that tells me that only one point of view is being given since it is natural for people to have differences of opinion.